Process of producing alpha-isocyanato ethers and products thereof



United States This invention relates to, and has as its principalobjects provision of, the reaction of isocyanic acid with alpha-betaunsaturated ethers and new a-isocyanato ethers obtained thereby.

Isocyanates are'a relatively reactive class of compounds which haveachieved considerable importance in recent years as intermediates. Theyreact with amine, carboxyl and hydroxyl groups. Polyisocyanates areparticularly important in view of the ease of polymer formation orcross-linking reactions with compounds containing a plurality ofreactive amine, hydroxyl, or other groups.

It has now been found that isocyanic acid reacts with ethers in which anether oxygen has only one ethylenic group directly attached thereto toproduce m-isocyanato ethers. New ethers thus produced include those ofFormula I:

N00 IJ I R- -O-Z-O-CR wherein R=H or lower alkyl (up to 4 carbons), R ishydrocarbon of not more than carbons, R is hydrocarbon of up to 6carbons and Z is hydrocarbon or oxygeninterrupted hydrocarbonhaving achain of at least two carbons, preferably an alkylene of 2-3 carbons;deithers of Formula II:

wherein R and R and Z are as previously defined; and ethers of Formula111:

R1 (III) :wherein R is an aliphatically saturated organic radical of upto 10 carbons, preferably of not more than 6, and R and R together canbe an alkylene radicaL Preferably ,R is hydrogen, R is hydrocarbon of upto 4 carbons,

atent O R is hydrocarbon of up to 3 carbons and R which ineludes alkyl,cycloalkyl, aryl, and aralkyl, generally has up to 6 carbons.

The process of this invention involves the addition of isocyanic acid tounsaturated ethers in which any ether oxygen has no more than oneethylenic group directly attached. The isocyanato (-NCO) group therebybecomes attached to the alpha unsaturated carbon. The addition isfacilitated by the presence of catalytic amounts of a strong acid.Although the presence of an added acid catalyst is not essential for thereaction, it is preferred that one be present. By acid catalyst is meanta compound having an open sextet-of electrons (see Wheland, AdvancedOrganic Chemistry, Wiley, N.Y., 1949, 2nd Ed., page 80, and Branch andCalvin, The Theory of Organic Chemistry, Prentice-Hall, N.Y., 1941,pages 186-7). The preferred acids in aqueous solutions have a pKa 'ofnot more than 3. Suitable strong acid catalysts include metaphosphoricacid, sodium bisulfite, sulfamic acid, boron trifluoride, and Zincchloride. The amount of acid catalyst is not critical although amountsof 0.1 to l 10% can be used. The catalyst is generally nonvolatile.

. 3 5 7 Patented Feb. "196?;

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The temperature is generally below C. and preferably 060 C. Althoughhigher temperatures can be used, they are generally avoided to preventpolymerization of vinyl ethers and decomposition of isocyanic acid. Thetime for the reaction is generally not long, e.g.,'timeS of from a fewminutes to an hour are sufiicient. The time and temperature aregenerally dependent upon the rate of introduction of isocyanic acid tothe ethylenically unsaturated ether.

Solvents or inert diluents can be present during the reaction. Althoughnot essential, it is preferred that inert diluents such as ethers (ethylether) or hydrocarbons (pentane, benzene, xylene) be present to moderatethe reaction and control the temperature.

The unsaturated ethers that can be used in the reaction are those thathave an ether oxygen to which there is -directly attached no more thanone ethylenic group, i.e., the compound must have the group These ethersgenerally have the vinylidene (CI-I =C)'-, including vinyl (CH =CH),group directly attached to .ether oxygen. Ethers of this general typethat are capable of the addition reaction with isocyanic acid includethose having only one ethylenic double bond such as wherein R ishydrogen and R is a hydrocarbon radical .ofup to 10 carbons, especiallyalkyl,-aryl, and with R alkylene. Examples of such vinyl-type ethers arevinyl pentyl ether and vinyl naphthyl ether. When R and R takentogether, are alkylene, they have 2-3 chain carbons. Vinyl ethers withtwo ethylenic'unsaturations of which not more thanone is directlyattached to any ether oxygen particularly useful in the processof thisinvention are those of the general formula wherein Z is a divalenthydrocarbon 'or' oxahydrocarbon radical free from ethylenic unsaturationand having at least two chain carbons, and in particular is ahydrocarbyl or oxygen-containing hydrocarbyl radical containinggenerally not more than 4 oxygens, e.g., the diradicals CH CH OCOCH CHOCOCH CH and Preferred are ethylene, triand tetramethylene, althougharylene, e.g., phenylene, can be present. A further important vinylether useful in the process of this invention contains an ester group asin the formula wherein R is a hydrocarbon radical of up to 6 carbonsincluding alkyl, e.g., CH C H C H alkenyl, e.g., CH =CH, CH =C(CH CHCH=CH--, CH CH=CH--CH=CH; alkynyl,e.'g., CHEC; and aryl, e.g.,- C HPreferred are those wherein R is an alkenyl and Z is an alkylene radicalof 2-3 carbons each.

Divinyl ethers contain two reactive ethylenic double bonds and areparticularly'desired since they give prod'ucts having two isocyanategroups, useful in polymer formation and modification. i f

Ethers that have only one vinyl group directly attached to ether oxygenand contain additional aliphatic unsaturated groups are alsoparticularly useful since isocyanic acid does not react with theadditional unsaturated group and the resulting compounds are convertibleto polymers; They are also useful as crosslinking agents or textiletreat ing agents.

The novel isocyanates can be separated from starting materials and inertdiluents by distillation. In general, the two reactants are employed insubstantially molar ratios (although the ratio can vary from about 1:2to :1).

The following examples further illustrate the process of this invention.

' EXAMPLE I I-Butoxyethyl lsocyanate CH =CHOC H +HNCO-2 CH CH(OC H NCOTo a mixture of 9.6 g. of isocyanic acid and 25 g. of vinyl butyl etherwas added at about 0 C. 10 ml. of dioxanecontaining 0.1 g. ofp-.toluenesulfonic acid. A mild exothermic reaction took place whichsubsided after a few minutes. Analysis by near infrared indicated thatall of the vinyl ether and isocyanic acid had been consumed. Ondistillation, there was obtained 7 g. of -1-butoxyethyl isocyanate, B.P.163 C./760 mm. or 69 C./38 mm., and 11 1.4080.

The-infrared spectrum of this product showed strong absorption at 3.4;].:(CH), 4.4 (NCO), and 8.85

as would be expected for l-butoxyethyl isocyanate. When a dioxauesolution of this compound was treated with a dropofconcentratedhydrochloric acid and then added to asolution' of 2,4dinitrophenylhydrazine, the, hydrazone of acetaldehyde (M12. 163-165 C.,no depression with an authentic sample) was obtained in. accordancewith'the indicated structure. I 1

Analysis.Calcd. for C H O N: C, 58.75; H, 9.09; N, 9.8; M.W. 143. Found:C, 59.17; H, 9.07; N, 10.27; MLWUISZ.

I-butoxyethyl isocyanate-was also obtained by adding a mixture of- 50-g. of vinyl butyl ether'and 14.9 ml. ofiisocyani'c'acid dropwise toa-stirred mixture of 50 ml. of diethyl ether and-0.1 g. ofp-toluene'sulfonic acid. The rate 'of addition was adjusted so'that atemperature of 3 8-'-40 C. was maintained. 'On distillation, there wasobtained 53 g'."(90% yield) of l-butoxyethyl isocyanate.

. mo on nNoo mo on H:

Amixture of 27.2 g. (.25 mole) of dihydropyran and 12.9 ml. (0.36 mole)of isocyanic acid, prepared at 80 C., was allowed to warm to 26 C.,whereupon an exothermic reaction occurred with the formation ofisocyanic acid polymer-(4.7 g.) along with Z-tetrahydropyranylisocyanate. On distillation, there was obtained 16 g. (51%) o e ahy opyryl ocyan e, -P- 2 m-; "H935,

4 EXAMPLE IV I-Phenoxyethyl Isocyanate C H OCH=CH +HNCO- C H OCH(CH NCOWhen a mixture of 6.5 g. (0.054 mole) of vinyl phenyl ether and 1.6 ml.(0.045 mole) of isocyanic acid was warmed to room temperature and then0.05 g. of p-tolueuesulfonic acid added, an exothermic reaction set inwhich subsided after 15-20 minutes. On distillation, 4.5 g. ofl-phenoxyethyl isocyanate, B.P. 42 C./0.4 mm. and 11 1.5057, wasobtained.

Analysis.Calcd. for C H O N: C, 66.30; H, 5.52; N, 8.60. Found: C,66.04;H, 5.57; N, 8.23.

The infrared spectrum of this product was in agreement with thel-phenoxyethyl isocyanate structure. Unequivocal evidence for thisstructure was provided by nuclear magnetic resonance, which showedmethyl, aromatic, and tertiary hydrogens in the ratio of 3 :5: 1.

EXAMPLE V 1 eBLltOJCY-I -Methylethyl lsocyanate G z= 0 C4H0 H 0 (Q s).24110) N00 To a mixture of 12.6 g. of isocyanic acid, 25 ml. of benzene,and 0.05 g. of p-toluenesulfonic acid was added dropwise over a periodof 24 minutes 22 g. of butyl isopropenyl ether (B.P. 114 C., 11 1.4076,prepared from 2,2-dibutoxypropane by the method of Crocker and Hall, J.Chem. Soc. 1952, 2052). The temperature rose from 29 C. to 44 C. duringthe period of addition. Distillation gave 22.2 g. (70%) ofl-butoxy-l-methylethyl isocyanate, B.P. 58 C./ 18 mm.; n 1.4102. Thestructure ,of the product was confirmed by infrared spectroscopicanalysis.

Analysis.Calcd. for CsHiso Nz N, 8.91. Found: N,

EXAMPLEv VI 1,1 -(Ethylenedi0xy)Diethyl Diz'socyanate CH :CHOCH CHOCH=CH +2HNCO+ OCNCH CH OCH CH OCH (CH )NCO The divinyl ether ofethylene glycol (22.8 g., 0.2 mole) was added with stirring to a mixtureof 30 ml. (0.84 mole) of isocyanic acid, ml. of benzene and 0.1 g. ofp-toluenesulfonic acid over a period of 20 minutes, during which timethe temperature rose to 55 C. The reaction mixture was stirred for 20additional minutes, and the product distilled under reduced pressure.After removal of the solvent and excess isocyanic acid, the residue wasdistilled through a short-pass still under a pressure of 0.3 mm. toseparate the distillable products from the polymeric products, and thedistillate redistilled through a short Vigreux column. There wasobtained 31.8 g. (80% yield) of 1,1'-(ethylenedioxy)diethyldiisocyanate, B.P. 65 C./0.6 mm.; 11 1.4360.

. Analysis.Calcd. for C H O N N, 14.00. Found: N, 13.93.

The divinyl ether of ethylene glycol was prepared in about 65% yield,according to the method of Favorskii (C.A., 38, 330 (1944)) by heating amixture of 220 g. of ethylene glycol, 12 g. of potassium hydroxidepellets and acetylenein an autoclave at C. for 22 hours.

In further studies, 1,1'-(ethylenedi0xy)diethyl diisocyanate reactedwith ethylene glycol at room temperature to form a clear, viscouspolymer. This diisocyanate reacted with hexamethylenediamine to form awhite polymer that melted about 150 C.

1,1'-(ethylenedioxy)diethyl diisocyanate has utility as an antistaticagent. For example, when a 4" x 8" piece of Dacron (Du Pont trademarkfor polyester fiber) (prepared from continuous filaments) was dippedinto a solution containing 0.68 g. of this diisocyanate, 12 ml. ofacetone and a drop of pyridine and allowed to dry, about 0.18 g. ofisocyanate was retained on the fabric. After standing at a relativehumidity of 65% and a temperature of 70 F. for 24 hours, the treatedfabric rapidly lost an electrical charge placed on it in marked contrastto the low loss of a similar charge by untreated fabric.

EXAMPLE VII 1,1'-(Oxydiethylenedioxy)Diethyl Diisocyanate OCNCH (CH 0CHCH OCH CH OCH(CH NCO A mixture of 15.8 g. of the divinyl ether ofdiethylene glycol and 9.1 g. of isocyanic acid cooled to 0 C. was addedover a period of one hour to a stirred mixture of 20 ml. of ether and0.05 g. of p-toluenesulfonic acid. An exothermic reaction occurred. Theresulting product was stirred with 1 g. of sodium bicarbonate. The1,1-(oxydi ethylenedioxy)diethy1 diisocyanate was distilled, boiling at160-170 C./0.3 mm.

Also available by the general procedure of Examples VI and VII are1,1'-(ethylenedioxy)dihexyl diisocyanate and1,1-dimethyl-1-1,1'-(ethylenedioxy)dipentyl diisocyanate and1,1-(succinatodiethylenedioxy)diethyl diisocyanate.

EXAMPLE VIII 2-(] -1socyanat0ethoxy)Ethyl M ethacrylare Pound:

initiator. Copolymers containing 25% and 50% of 2-(1- isocyanato)ethylmethacrylate air-dried to hard tough coatings on glass; whereas,unmodified polymers of ethyl acrylate were soft, tacky, and soluble inxylene and other solvents. These copolymers were used as adhesives forpolyvinyl fluoride and polyethylene terephthalate films.

When 2-vinyloxyethyl acetate is used in place of the methacrylate in theabove procedure, there isobtained 2-(1-isocyanatoethoxy)ethyl acetate.By similar method there can also be obtained 2-(1-isocyanatoethoxy)ethylpropiolate, 2-(1-isocyanatoethoxy)ethyl sorbate, 2-(1-iso cyanatoethoxy)ethyl benzoate, 3-( 1-isocyanatoethoxy)- propyl methacrylate, and 2-[2-(1-isocyanatoethoxy)- ethoxy]ethyl methacrylate.

When the new isocyanates of this invention are heated to theirdecomposition temperature, generally above about 200 C., vinyl ethersand isocyanic acid are regenerated and can be employed directly forcrosslinking of polyhydroxylated polymers.

When the general conditions of the examples were repeated with divinylether and furan, no addition reaction was observed.

The new isocyanates of this invention are generally useful in pesticideapplications. The product of Example III (Z-tetrahydropyranylisocyanate) when applied as a 1% solution in acetone kills insects suchas two-spotted mite.

The u-isocyanato ethers of this invention are converted to ureas byreaction in acetone solution at room temperature with an amine havinghydrogen on amino nitrogen. The ureas thus obtained, and in particularthose from aniline, are fungicidal. For example, the phenylureascorresponding to the products of the exampics when applied as a 0.2percent solution on tomato foliage gave substantial protection againstthe early blight fungus.

New isocyanato ethers that are particularly preferred are thosecontaining a plurality of cyanato groups. These new compounds are usefulas treating agents for polymers, e.g., as antistatic agents. They alsoreact with glycols and diamines to form new polymers useful in theproduction of fibers.

Since obvious modifications in the invention will be evident to thoseskilled in the chemical arts, I propose to be bound solely by theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is-claimed are defined as follows:

1. The process of preparing an a isocyanato ether which comprisesreacting isocyanic acid and an ether in which one, and only one, of thecarbons attached to the ether oxygen carries a carbon-to-carbon doublebond at a temperature between about and 75 C., said ether beinghydrocarbon except for the ether function.

2. The process of claim 1 accomplished in the presence of an acidcatalyst.

3. The process of claim 1 accomplished in an inert diluent.

4. The process of preparing an a-isocyanato ether which comprisesreacting isocyanic acid and a monovinyl ether at a temperature betweenabout -80 and 75 C.

5. The process of preparing an u-isocyanato ether which comprisesreacting isocyanic acid and vinyl butyl ether at a temperature betweenabout 80 and 75 C.

6. The process of preparing and u-isocyanato ether which comprisesreacting isocyanic acid and vinyl ethyl ether at a temperature betweenabout 80 and 75 C.

7. The process of preparing an oc-isocyanato ether 3 which comprisesreacting isocyanic acid and dihydropyran at a temperature between about80 and 75 C.

8. The process of preparing an a-isocyanato ether which comprisesreacting isocyanic acid and vinyl phenyl ether at a temperature betweenabout -80 and 75 C.

9. The process of preparing an a-isocyanato ether which comprisesreacting isocyanic acid and a divinyl diether in which each ether oxygenis connected to a vinyl radical and the two ether oxygens are connectedto each other by a member of the group consisting of hydrocarbon andoxygen-interrupted hydrocarbon radicals of at least two carbons at atemperature between about 80 and 75 C., said diether being hydrocarbonexcept for the ether functions.

10. The process of preparing an a-isocyanato ether which comprisesreacting isocyanic acid and the divinyl diether of ethylene glycol.

'11. The process of preparing an a-isocyanato ether which comprisesreacting isocyanic acid and an ether having at least two chain oxygens,the first of said oxygens being an ether oxygen attached to a vinylradical and, through a member of the group consisting of hydrocarbon andoxygen-interrupted hydrocarbon radicals of at least two carbons, to thesecond of said chain oxygens, said second oxygen being bonded to acarbonyl group attached to a hydrocarbon radical, at a temperaturebetween about 80 and 75 C., the reactant ether being hydrocarbon exceptfor ether oxygen.

12. The process of preparing an a-isocyanato ether which comprisesreacting isocyanic acid and 2-vinyloxyethyl methacrylate at atemperature between about --80 and 75 C.

13. An a-isocyanato ether of up to 3-0 carbons in which one bond of theether oxygen is attached to a carbon bonded to the isocyanate group andat least one other carbon and the other bond of the ether oxygen isattached to a member of the group consisting of monovalent and divalenthydrocarbon radicals, the second valence of any divalent hydrocarbonradical being attached to the carbon bonded to the isocyanate group.

'14. Z-tetrahydropyranyl isocyanate. 15. l-phenoxyethyl isocyanate.

16. A, compound having two ether, oxygens andup to 30 carbon atoms, saidether oxygens being connected -.to each other-through a member of thegroup consisting 5 of hydrocarbon and oxygen-interruptedhydrocarbonradicals of-at least two carbons, each of said ether oxygens beingv alsoconnected tora carbon bearing an isocyan'ate radical.

17. 1,1'-(ethy1enedioxy) diethyl diisocyanate. 18. An-ethenof up to v30-carbons having at least .two

,chain oXygens one of which is an-ether oxygen attached directly to acarbon bearing an isocyanate radical and,

* through a member of the group consisting of hydrocarbon andoxygen-interrupted hydrocarbon radicals of at least two carbons, to thesecond of said chain oxygens,-said second oxygen beingbonded to acarbonyl group attached .-to' ahydrocarbon radical.

References Cited in the file of this patent UNITED-STATES PATENTSSchweitzer Oct. 22, 1946 Melamcd et al Dec. 13, 1955 OTHER" REFERENCESones et; al.:' Journal American Chemical Society, yol.

46, pages25 18-25 33 1924).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,076,788 February 5, 1963 Fred W, Hoover It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 2, line 38, the formula should appear as shown below instead ofas in the patent:

CH =CH-O,Z-OCH=CH column 5, line 21, beginning with andl,l"-dimethyl-"=. strike out all to and including "diissocyanate," inlines 22 and 23, and insert instead and l ,l"dimethyl=l ,'l--(ethylenedioxy) dipentyl diisocyanateo column 6, line 32, for "and"read an line 63, for the terminal period substitute and carbonyl. -u

Signed and sealed this 3rd day of September 1963,,

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

1. THE PROCESS OF PREPARING AN A-ISOCYANATO ETHER WHICH COMPRISESREACTING ISOCYANIC ACID AND AN ETHER IN WHICH ONE, AND ONYL ONE, OF THECARBONS ATTACHED TO THE ETHER OXYGEN CARRIES A CARBON-TO-CARBON DOUBLEBOND AT A TEMPERATURE BETWEEN ABOUT -80 AND 75*C., SAID ETHER BEINGHYDROCARBON EXCEPT FOR THE ETHER FURNCTION.